基于灰关联分析的天津市气溶胶消光特征研究

根据天津市秋季(2006年10月10日～20日)消光系数(bext)、PM2.5、SO2、NOX、NO2、O3质量浓度及相对湿度监测结果,利用灰色关联分析法分析大气消光系数同空气中的几种主要污染要素的相关性。结果表明,与消光系数有关的几种主要指标的灰关联度序为PM2.5NOXRHNO2O3,其中PM2.5与消光系数的灰关联系数达到0.905,远高于其他相关指标。同时对PM2.5和消光系数相关分析表明,监测期间天津市PM2.5质量消光系数为6.04m2/g。     

Risk assessment and prioritisation of contaminated sites on the catchment scale

Contaminated sites pose a significant threat to groundwater resources worldwide. Due to limited available resources a risk-based prioritisation of the remediation efforts is essential. Existing risk assessment tools are unsuitable for this purpose, because they consider each contaminated site separately and on a local scale, which makes it difficult to compare the impact from different sites. Hence a modelling tool for risk assessment of contaminated sites on the catchment scale has been developed. The CatchRisk screening tool evaluates the risk associated with each site in terms of its ability to contaminate abstracted groundwater in the catchment. The tool considers both the local scale and the catchment scale. At the local scale, a flexible, site specific leaching model that can be adjusted to the actual data availability is used to estimate the mass flux over time from identified sites. At the catchment scale, a transport model that utilises the source flux and a groundwater model covering the catchment is used to estimate the transient impact on the supply well. The CatchRisk model was tested on a groundwater catchment for a waterworks north of Copenhagen, Denmark. Even though data scarcity limited the application of the model, the sites that most likely caused the observed contamination at the waterworks were identified. The method was found to be valuable as a basis for prioritising point sources according to their impact on groundwater quality. The tool can also be used as a framework for testing hypotheses on the origin of contamination in the catchment and for identification of unknown contaminant sources.     

Transport of Sr2+ and SrEDTA2- in partially-saturated and heterogeneous sediments

Strontium-90 has migrated deep into the unsaturated subsurface beneath leaking storage tanks in the Waste Management Areas (WMA) at the U.S. Department of Energy's (DOE) Hanford Reservation. Faster than expected transport of contaminants in the vadose zone is typically attributed to either physical hydrologic processes such as development of preferential flow pathways, or to geochemical processes such as the formation of stable, anionic complexes with organic chelates, e.g., ethylenediaminetetraacetic acid (EDTA). The goal of this paper is to determine whether hydrological processes in the Hanford sediments can influence the geochemistry of the system and hence control transport of Sr(2+) and SrEDTA(2-). The study used batch isotherms, saturated packed column experiments, and an unsaturated transport experiment in an undisturbed core. Isotherms and repacked column experiments suggested that the SrEDTA(2-) complex was unstable in the presence of Hanford sediments, resulting in dissociation and transport of Sr(2+) as a divalent cation. A decrease in sorption with increasing solid:solution ratio for Sr(2+) and SrEDTA(2-) suggested mineral dissolution resulted in competition for sorption sites and the formation of stable aqueous complexes. This was confirmed by detection of MgEDTA(2-), MnEDTA(2-), PbEDTA(2-), and unidentified Sr and Ca complexes. Displacement of Sr(2+) through a partially-saturated undisturbed core resulted in less retardation and more irreversible sorption than was observed in the saturated repacked columns, and model results suggested a significant reservoir (49%) of immobile water was present during transport through the heterogeneous layered sediments. The undisturbed core was subsequently disassembled along distinct bedding planes and subjected to sequential extractions. Strontium was unequally distributed between carbonates (49%), ion exchange sites (37%), and the oxide (14%) fraction. An inverse relationship between mass wetness and Sr suggested that sandy sediments of low water content constituted the immobile flow regime. Our results suggested that the sequestration of Sr(2+) in partially-saturated, heterogeneous sediments was most likely due to the formation of immobile water in drier regions having low hydraulic conductivities.     

Analysis of trace dicyandiamide in stream water using solid phase extraction and liquid chromatography UV spectrometry

An improved method for trace level quantification of dicyandiamide in stream water has been developed. This method includes sample pretreatment using solid phase extraction. The extraction procedure (including loading, washing, and eluting) used a flow rate of 1.0 mL/min, and dicyandiamide was eluted with 20 mL of a methanol/acetonitrile mixture (V/V = 2:3), followed by pre-concentration using nitrogen evaporation and analysis with high performance liquid chromatography–ultraviolet spectroscopy (HPLC–UV). Sample extraction was carried out using a Waters Sep-Pak AC-2 Cartridge (with activated carbon). Separation was achieved on a ZIC^®-Hydrophilic Interaction Liquid Chromatography (ZIC-HILIC) (50 mm × 2.1 mm, 3.5 μm) chromatography column and quantification was accomplished based on UV absorbance. A reliable linear relationship was obtained for the calibration curve using standard solutions (R² > 0.999). Recoveries for dicyandiamide ranged from 84.6% to 96.8%, and the relative standard deviations (RSDs, n = 3) were below 6.1% with a detection limit of 5.0 ng/mL for stream water samples.     

气相分子吸收光谱法测定氨氮校准曲线斜率、截距参考值研究

主要阐述了气相分子吸收光谱法测定氨氮的校准曲线斜率、截距参考值的分析.文章收集了临安市环境监测站实验室自2012年以来气相分子吸收光谱法氨氮校准曲线制作的一系列原始数据,并通过数理统计方法对校准曲线、残余标准偏差、斜率扩展不确定度、截距扩展不确定度开展了详细讨论,得出气相分子吸收光谱法氨氮校准曲线截距a值、斜率b值实验室参考值.此结果对实验室分析人员判定氨氮项目校准曲线制作是否合格具有一定的参考价值.     

高效液相色谱-电感耦合等离子体质谱联用测定生物样品中的有机汞

建立了酸提取-高效液相色谱-电感耦合等离子体质谱联用技术(HPLC-ICP-MS)测定生物样品中甲基汞、乙基汞、苯基汞等3种有机汞的分析方法。鱼肉和贝类样品经盐酸消解,苯萃取,硫代硫酸钠溶液反萃取后,采用醋酸铵/L-半胱氨酸缓冲盐及甲醇体系组成的流动相按一定比例进行梯度洗脱,经前处理的生物样品在液相色谱中经C18柱分离后,进入电感耦合等离子体质谱检测其甲基汞、乙基汞和苯基汞的浓度。3种有机汞化合物均在0.50~50.0μg/L范围内呈现良好的线性关系,线性相关系数(r)均大于0.9998。方法检出限为0.010~0.038mg/kg;3种有机汞样品加标的RSD均小于12.2%;两个水平的加标回收率在50.8~129%。     

超高效液相色谱-串联质谱法同时分析地下水中24种内分泌干扰物

建立了基于超高效液相色谱-串联质谱法同时测定地下水中9种雌激素、5种雄激素、3种肾上腺皮质激素、4种酚类和3种非甾类激素共24种内分泌干扰物的方法。在活化后的MCX固相萃取柱中加入水样,再加入pH=5的水溶液淋洗,随后用碱化乙腈(4.5%,体积分数)洗脱。收集洗脱液并用氮气吹至近干后,用甲醇定容。采用Poroshell 120 Bonus-RP色谱柱(2.7 μm,100 mm×2.1 mm),以0.1%氨水溶液-乙腈为流动相进行梯度洗脱,实现液相分离。质谱检测采用MRM模式进行采集,通过正负离子模式切换同时进行测定,使用内标法定量。检测结果显示,目标物在线性范围内,决定系数R²均大于0.995,方法检出限为0.05~2.00 ng/L,加标回收率为68.8%~108%。该方法灵敏度高、准确度好,具有较强的实用价值。     

The evolution of mass balance models of persistent organic pollutant fate in the environment

Current approaches to modelling the fate of persistent organic pollutants (POPs) in the environment have evolved in response to four dominant characteristics of these substances; namely: (1) the presence of POPs in virtually all environmental phases and the ease with which they move from one to the other requires multi-compartmental modelling. Describing transport across phase boundaries becomes as, or even more, important as quantifying transport within the phases; (2) POPs may persist in the environment for many decades. For chemicals that 'have time', concepts such as equilibrium partitioning and steady-state become more important than for short-lived substances whose fate is more controlled by the rates of transformation; (3) measuring POPs is difficult and expensive and observed concentrations of POPs are not available in high spatial or temporal resolution. Consequently, high resolution tends not to be a high priority in POP models; and (4) detrimental effects of POPs often manifest themselves in top predators, which has led to a focus on modelling biotic uptake and transfer within food chains. The task of building a POPs model is viewed as combining the four 'building blocks' of partitioning, transport, transformation and source data with the help of the law of the conservation of mass. Process models, evaluative models, models of real local, regional and global fate, as well as biological uptake models are presented and references to numerous examples are provided. An attempt is made to forecast future directions in the field of POPs modelling. It is expected that modelling techniques that do not rely on quantitative emission estimates as well as approaches that take into account spatial, temporal and climatic variability as well as parameter uncertainty will increase in importance. Finally, the relationship between modelling POPs and models of other pollutant issues is addressed, as are potential interactions between POPs and pollutant issues such as eutrophication, acidification and global climate change.